HIV 2 Flashcards
major determinant of HIV pathogenesis
-virus tropism for CD4 expressing T cells and macrophage lineage cells which are multipotent stem and progenitor cells
how does one get HIV induced immunosuppression (AIDS)
reduction in number of CD4 T cells
what happens immediately after infection with HIV
long period of silent but dynamic virus replication and diversification with high host cell turnover
what does the HIV virus kill or decimate
helper and delayed type hypersensitivity functions of the immune response
how does HIV enter the body
in infected macrophages
type of infection one has if the virus is in macs vs. T cells
in macs - persistent infection
T cell - lytic and latent infection
what occurs if HIV is present in the macrophages
- mac is a reservoir for the virus
- dysfunction
- virus release
- cytokine release and dysregulation of immune function
what is one susceptible to once HIV proceeds to AIDS
- severe systemic opportunistic infections
- Kaposi’s sarcoma
- lymphoma
HIV virus enters the body in infected macrophages. How then do the T cells become infected?
- dendritic cells accumulate the virus on their surface without internalizing them
- they then carry the virus to lymph nodes for effective infection of the T cells
mechanism of immune evasion of HIV
- antigenic variation
- carb masking of target epitopes
- conformational changes by viral envelopes to mask neutralization targets
- downregulation of HLA
- viral latency in resting T cells and antigen presenting cells
what are the cytopathic effects of HIV
syncytial formation due to the fusion of infected microglia and macrophages in the brain –> HIV encephalopathy
what cannot be detected in the window of acute infection (first year after infection)
antibody of HIV – hence have to use another means of testing
what is the best test to use to detect HIV – detecting the virus as soon as 10 days post infection? why is it so effective?
RNA test
tests for the virus directly (viral load)
type of test is used to detect HIV as soon as 3 weeks post infection? type of sample needed?
antibody and antigen (part of virus itself)
blood sample only
what STD can be detected with NAAT
c. trichomatis and n. gonorrhea
what is the goal of HIV treatment?
to get HIV RNA levels below assay detection limitis
it is important to monitor therapy. what happens if one is taken off antiretroviral therapy (ART) after many years of treatment?
viral replication starts back up again
what does the HIV viral load tell you
how rapidly the progression of the disease is occurring
how do you monitor people on antiretroviral therapy (ART)
viral load monitoring
what occurs in the window period (first year)
- negative HIV test
- viral load high
- high risk of transmission
what is the goal in opportunistic infection
to prevent them because they lead to higher chance of death
when do you know that HIV has proceeded to AIDS
- very low T cell count
- presence of one or more specific infections
- presence of certain cancer
what are the bacterial infection associated with AIDS
salmonellosis, tuberculosis, bacterial pneumonia, bartonella henselae, mycobacteria avium complex (MAC)
ST BBM
common cause of pneumonia in AIDS patients
strep pneumonia
other causes of pneumonia in AIDS patients
h. influenza, staph aureus, pseudomonas
virulence factors of strep pneumonia
- colonize oropharynx (surface protein adhesions)
- spread into normally sterile tissues (pneumolysin and IgA protease)
- stimulate local inflammatory response
- evade phagocytic killing (polysaccharide capsule)
when does an AIDs patient get mycobacterium avium complex
in advanced HIV infection and CD4 count is less than 50
body’s response to mycobacterium avium complex (mycobacterium avium and mycobacterium intracellulare)
- immunocompetent - asymptomatic, solitary nodules, chronic pulmonary localized disease
- immunocompromised like AIDS patient - disseminated
symptom of mycobacterium avium complex (mycobacterium avium and mycobacterium intracellulare)
night sweats, weight loss, abdominal pain, fatigue, diarrhea, anemia
what is the leading cause of death in people with AIDS
tuberculosis (1/3 of people with HIV have tuberculosis as well)
million of people infected with both HIV and TB – this is referred to as?
twin epidemics
